in pennsylvania this afternoon, mitt romney made this bold promise. >> you're right, they're wrong, and we'll win pennsylvania and take the white house. >> reporter: but for that to happen with polls showing him trailing the president, analysts say romney must change the trajectory of the race. in a discussion, he acknowledged this is an important opportunity. >> and i think it will give people a chance to understand where we actually stand, as opposed to where our opposition thinks we stand. and then they can make a more informed choice. >> reporter: while both candidates are practicing in private, president obama held a closed-door session this afternoon. and publicly their campaigns are showering the opponents with praise. a message from one expert outlines romney's skills as a prepared, aggressive, debater. the romney campaign is touting president obama's natural gifts and the extensive seasoning under the bright lights of the bright stage. today, in a mock debate, senator john kerry dismissed the idea that the republican nominee is an inexperienced debater, pointing to more than 20 debates.